Chucking process and system for substrate processing chambers

ABSTRACT

The present disclosure relates to methods and systems for chucking in substrate processing chambers. In one implementation, a method of chucking one or more substrates in a substrate processing chamber includes applying a chucking voltage to a pedestal. A substrate is disposed on a support surface of the pedestal. The method also includes ramping the chucking voltage from the applied voltage, detecting an impedance shift while ramping the chucking voltage, determining a corresponding chucking voltage at which the impedance shift occurs, and determining a refined chucking voltage based on the impedance shift and the corresponding chucking voltage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent applicationSer. No. 62/815,674, filed Mar. 8, 2019, which is herein incorporated byreference.

BACKGROUND Field

Aspects of the present disclosure relate generally to methods andsystems for operating substrate processing chambers, including methodsof chucking substrates.

Description of the Related Art

During processing of a substrate, sometimes the substrate is chucked toa pedestal within a substrate processing chamber. For example, asubstrate might be chucked to a pedestal during processing when thesubstrate is bowed. However, due to variances in the pedestal'scharacteristics, and/or variances in the substrate's characteristics, itis difficult, costly, and time-consuming to determine a chucking voltagethat should be applied to the pedestal during processing. If too low ofa chucking voltage is applied, arcing can occur during substrateprocessing. The substrate can also experience backside damage if toohigh of a chucking voltage is applied, leading to defects and loweryield of substrate processing operations.

Therefore, there is a need for an improved method of chucking asubstrate that reduces or eliminates backside damage and arcing andimproves yield in a cost-effective manner.

SUMMARY

Implementations of the present disclosure generally relate to methodsand systems for operating substrate processing chambers, includingmethods of chucking substrates.

In one implementation, a method of chucking one or more substrates in asubstrate processing chamber includes applying a chucking voltage to apedestal. A substrate is disposed on a support surface of the pedestal.The method also includes ramping the chucking voltage from the appliedvoltage, detecting an impedance shift while ramping the chuckingvoltage, and determining a corresponding chucking voltage at which theimpedance shift occurs. The method also includes determining a refinedchucking voltage based on the impedance shift and the correspondingchucking voltage.

In one implementation, a method of chucking one or more substrates in asubstrate processing chamber includes applying a chucking voltage to apedestal using a preselected value. A substrate is disposed on a supportsurface of the pedestal. The method also includes detecting an impedanceshift, determining a refined chucking voltage based on the impedanceshift, and adjusting the applied chucking voltage using the refinedchucking voltage.

In one implementation, a controller for substrate processing chambersystems includes a processor. The controller includes a set of computerinstructions that, when executed, instruct the processor to cause adirect current voltage generator to apply a chucking voltage to apedestal. The set of computer instructions, when executed, cause animpedance detector to detect an impedance shift of a radio frequencyenergy generator, and determine a refined chucking voltage based on theimpedance shift.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the disclosurecan be understood in detail, a more particular description of thedisclosure, briefly summarized above, may be had by reference toimplementations, some of which are illustrated in the appended drawings.It is to be noted, however, that the appended drawings illustrate onlycommon implementations of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective implementations.

FIG. 1 is a partial schematic cross-sectional view of a substrateprocessing chamber system, according to one implementation.

FIG. 2 is a schematic illustration of a method of chucking a substratein a substrate processing chamber, according to one implementation.

FIG. 3 is an illustration of an image showing an impedance shift,according to one implementation.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneimplementation may be beneficially utilized on other implementationswithout specific recitation.

DETAILED DESCRIPTION

The present disclosure relates to methods and systems for chucking asubstrate in a substrate processing chamber. FIG. 1 illustrates apartial schematic cross-sectional view of a substrate processing chambersystem 101, according to one implementation. The substrate processingchamber system 101 includes a chamber 100 having a pedestal 138 disposedtherein. The chamber 100 may be, for example, a chemical vapordeposition (CVD) chamber, a plasma enhanced CVD (PECVD) chamber, or aphysical vapor deposition (PVD) chamber. The chamber 100 has a chamberbody 102 and a chamber lid 104. The chamber body 102 includes aninternal volume 106 therein and a pumping path 108. The internal volume106 is the space defined by the chamber body 102 and the chamber lid104. The pumping path 108 is a path formed in the chamber body 102coupled to a pumping volume 112 formed in a pumping plate 114. Thepumping path 108 facilitates removal of gases from the internal volume106.

The chamber 100 includes a gas distribution assembly 116 coupled toand/or disposed in the chamber lid 104 to deliver a flow of one or moregases into a processing region 110. The processing region 110 includes aportion of the internal volume 106 located between the substrate support138 and the chamber lid 104. The gases delivered by the gas distributionassembly 116 may include, for example, one or more processing gases(such as one or more inert gases and/or one or more precursor gases). Inone example, the one or more processing gases include a precursor gasthat includes tetraethyl orthosilicate (TEOS) to form film on thesubstrate 136. The gas distribution assembly 116 includes a gas manifold118 coupled to a gas inlet passage 120 formed in the chamber lid 104.The gas manifold 118 receives a flow of gases from one or more gassources 122 (two are shown). The flow of gases received from the one ormore gas sources 122 distributes across a gas box 124, flows through aplurality of openings of a backing plate 126, and further distributesacross a plenum 128 defined by the backing plate 126 and a faceplate130. The flow of gases then flows into the processing region 110 of theinternal volume 106 through a plurality of openings 132 of the faceplate130. A pump 133 is connected to the pumping path 108 by a conduit 134 tocontrol the pressure within a processing region 110 and to exhaust gasesand byproducts from the processing region 110 through the pumping volume112 and pumping path 108.

The internal volume 106 includes a pedestal 138 that supports asubstrate 136 within the chamber 100 on a support surface 138 a of thepedestal 138. The pedestal 138 includes an electrode 140 disposed withinthe pedestal 138. The electrode 140 may include a conductive mesh, suchas a tungsten-containing, copper-containing, or molybdenum-containingconductive mesh. The electrode 140 may include any material used forheating, including an alternating current (AC) coil. The electrode 140is coupled to a power source 159, such as a direct current (DC) voltagegenerator. The electrode 140 is configured to supply a chucking voltageto the pedestal 138 that is received from the DC voltage generator 159.The chucking voltage applies a chucking force to the substrate 136 suchthat the substrate 136 is chucked to the support surface 138 a of thepedestal 138. Electrostatic forces applied to the substrate 136 resultin the substrate being pulled down toward the electrode 140 tofacilitate chucking the substrate 136 to the support surface 138 a. Thechucking force acting on the substrate 136 facilitates eliminating a bowof the substrate 136, or flattening the substrate 136.

The electrode 140 is coupled to a radio frequency (RF) energy generator156. The electrode 140 is configured to propagate RF received from theRF energy generator 156 through the pedestal 138 and into the processingregion 110. The electrode 140, for example, can propagate RF energywhile one or more processing gases are present in the processing region110 such that a plasma 141 is generated in the processing region 110.

The electrode 140 is coupled to a heating power source 180 that suppliesheating power to the electrode 140. The heating power may be, forexample, an alternating current (AC). The electrode 140 is configured toheat the pedestal 138 with the heating power received from the heatingpower source 180.

The electrode 140 is coupled to the RF energy generator 156, the heatingpower source 180, and the DC voltage generator 159 through a conductiverod 160 and a matching circuit 158. An impedance detector 190 is coupledto the RF energy generator 156. The impedance detector 190 is configuredto detect an impedance shift of the RF energy generator 156 while the DCvoltage generator 159 applies a chucking voltage to the pedestal 138,through the electrode 140. In one embodiment, which can be combined withother embodiments, the impedance detector 190 is additionally oralternatively coupled to other components of the substrate processingchamber system 101. For example, the impedance detector 190 may becoupled to, and configured to detect an impedance shift in, one or moreof the substrate 136, pedestal 138, electrode 140, heating power source180, DC voltage generator 159, chamber body 102, chamber lid 104,support surface 138 a, faceplate 130, backing plate 126, and/or a secondRF energy generator 166. The present disclosure contemplates that theimpedance detector 190 can be configured to detect an impedance shift ofany component of the substrate processing chamber system 101, and to usesuch information in accordance with aspects disclosed herein.

The pedestal 138 is movably disposed in the internal volume 106 by astem 142 coupled to a lift system. Movement of the pedestal 138facilitates transfer of the substrate 136 to and from the internalvolume 106 through a slit valve formed through the chamber body 102. Thepedestal 138 may also be moved to different processing positions forprocessing of the substrate 136. The pedestal 138 may also have openingsdisposed therethrough, through which a plurality of lift pins 150 may bemovably disposed. In the lowered position, the plurality of lift pins150 are projected from the pedestal 138 by contacting a lift plate 152coupled to a bottom 154 of the chamber body. Projection of the lift pins150 places the substrate 136 in a spaced-apart relation from thepedestal 138 to facilitate the transfer of the substrate 136.

During substrate processing, as gases flow into the processing region110, the electrode 140 heats the pedestal 138. Also during substrateprocessing, the electrode 140 propagates radio frequency (RF) energy,alternating current (AC), or direct current (DC) to facilitate plasmageneration in the processing region 110 and/or to facilitate chucking ofthe substrate 136 to the pedestal 138. The heat, gases, and energy fromthe electrode 140 facilitate deposition of a film onto the substrate 136during substrate processing.

The faceplate 130, which is grounded via coupling to the chamber body102, and the electrode 140 facilitate generation of plasma 141. Forexample, the RF energy generator 156 provides RF energy to the electrode140 within the pedestal 138 to facilitate generation of plasma 141between the pedestal 138 and the faceplate 130 of the gas distributionassembly 116. The RF energy generator 156 connects to ground 171. Asecond RF energy generator 166 also is configured to provide RF energyto the chamber 100. The second RF energy generator 166 is connected toground 173. Although a second RF energy generator 166 is illustrated,the present disclosure contemplates that other power sources may be usedin place of or in conjunction with the second RF energy generator 166.For example, a second alternating current (AC) power source or a seconddirect current (DC) power source may be used. The present disclosurecontemplates that the second AC power source and/or the second DC powersource may be coupled to the impedance detector 190.

The substrate processing chamber system 101 includes a controller 192that is configured to control one or more of the components of thesubstrate processing chamber system 101. The controller 192 includes acentral processing unit (CPU) 193, support circuitry 194, and memory 195containing associated control software 196. The CPU 193 may include aprocessor. The control software 196 includes a set of computerinstructions that, when executed, instruct the CPU 193 of the controller192 to cause one or more operations to be carried out using one or morecomponents of the substrate processing chamber system 101. Thecontroller 192 may include any form of a general purpose computerprocessor that can be used in an industrial setting for controllingvarious chambers and sub-processors. The CPU 193 may use any suitablememory 195, such as random access memory, read only memory, floppy diskdrive, compact disc drive, hard disk, or any other form of digitalstorage, local or remote. Various support circuits may be coupled to theCPU 193 for supporting the chamber 100. The controller 192 may becoupled to another controller that is located adjacent individualchamber components. Bi-directional communications between the controller192 and various other components of the chamber 100 are handled throughnumerous signal cables collectively referred to as signal buses, some ofwhich are shown in FIG. 1.

The controller 192 illustrated in FIG. 1 is configured to control atleast the one or more gas sources 122, pump 133, RF energy generator156, DC voltage generator 159, second RF energy generator 166, heatingpower source 180, and impedance detector 190. In one embodiment, whichcan be combined with other embodiments, the controller 192 is configuredto, when executed by a processor (such as the CPU 193), cause one ormore of the operations illustrated in method 200 of FIG. 2 to be carriedout. In one example the control software 196 includes a set of computerinstructions that, when executed, instruct the CPU 193 of the controller192 to cause one or more operations illustrated in method 200 of FIG. 2to be carried out.

FIG. 2 is a schematic illustration of a method 200 of chucking asubstrate in a substrate processing chamber. At operation 201, achucking voltage is applied to a pedestal with a substrate disposed on asupport surface of the pedestal and/or radio frequency (RF) energy issupplied to a substrate processing chamber. In one embodiment, which canbe combined with other embodiments, the chucking voltage is appliedusing a preselected value for the chucking voltage. The preselectedvalue may be obtained based on, for example, the specifications of aprocessing chamber, substrate, pedestal, or electrode, or a materialthereof. The preselected value could be obtained from prior substrateprocessing or chucking operations. In one example, the preselected valueis obtained using one or more experimental runs when a new pedestal,chamber, and/or substrate is used in substrate processing operations.

In optional operation 203, a plasma, such as an inert plasma, isgenerated. At optional operation 205, the chucking voltage is ramped upor down until an impedance shift occurs. Alternatively, the chuckingvoltage may be ramped up from the applied voltage to a second greatervoltage, in order to identify the voltage between the applied voltageand the second greater voltage at which the impedance shift occurs. Inone embodiment, which can be combined with other embodiments, the secondgreater voltage is a preselected value. An impedance shift is detectedat operation 207. The impedance shift signals that the substrate ischucked to the support surface of the pedestal.

In one embodiment, which can be combined with other embodiments, thechucking voltage is ramped up or down in one or more voltage incrementsuntil the impedance shift occurs. In one example, the chucking voltageis ramped upward in increments of 50 Volts that are each applied for 5or more seconds (such as 10 or more seconds) to allow impedance sensorstabilization, until the impedance shift occurs. In one example, thechucking voltage is ramped downward in increments of 100 Volts that areeach applied for 5 or more seconds (such as 10 or more seconds) untilthe impedance shift occurs.

The impedance shift is a shift in impedance of at least a predeterminedamount, such as 0.5 Ohms or more. In one embodiment, which can becombined with other embodiments, a first impedance value is measuredafter the chucking voltage is applied at block 201 for a predeterminedtime period, such as a time of 5 or more seconds (such as 10 or moreseconds). In such an embodiment, a second impedance value is measuredafter ramping the chucking voltage at block 205 and applying the rampedchucking voltage for another equal or different time period, such asabout 5 or more seconds (such as 10 or more seconds). Applying thechucking voltage for the predetermined time period allows the impedancevalues to settle for accurate measurements. The difference between thefirst impedance value and the second impedance value indicates theimpedance shift. A shift is deemed to occur when the delta betweenmeasured impedance values exceeds a predetermined threshold amount. Inone example, a shift of 0.5 Ohms or more indicates that the substrate ischucked and/or a bow of the substrate is reduced or eliminated. It is tobe noted however, other shift values are contemplated.

In one embodiment, which can be combined with other embodiments, animpedance shift is used to verify that the substrate is chucked and/or abow of the substrate is reduced or eliminated. In such an embodiment, animpedance shift at block 207 of a value less than a target value, suchas 0.1 Ohms or less, is used to verify the substrate is chucked to apedestal. In one example, a second impedance shift is measured after theimpedance shift is measured at block 207. If the second impedance shiftis equal to or less than a target value, such as 0.1 Ohms or less, thenchucking of the substrate to the pedestal is verified. If the secondimpedance shift is greater than the predetermined target value forconfirming chucking, then it is possible that the substrate has becomeat least partially un-chucked from pedestal.

Not to be bound by theory, it is believed that the impedance shift iscaused by a change in flow of electrical charge between the substrateand other component(s) of a substrate processing chamber system. Forexample, chucking of the substrate can remove a bow of the substratesuch that the substrate flattens out toward the support surface of thepedestal, reducing one or more gaps between the substrate and thesupport surface. Reducing one or more gaps between the substrate and thesupport surface causes a change in the flow of electric charge betweenthe substrate and other component(s) such as the pedestal. The change inflow of electric charge causes an impedance shift in one or morecomponents of the substrate processing chamber system.

In one embodiment, which can be combined with other embodiments, theoperation of detecting the impedance shift includes measuring theimpedance shift. Devices such as impedance detectors (for example theimpedance detector 190 described above) may be used to detect and/ormeasure the impedance shift. In one embodiment, which can be combinedwith other embodiments, the impedance shift is an impedance shift of aradio frequency (RF) energy generator that supplies radio frequencyenergy to the substrate processing chamber. The present disclosurecontemplates that the impedance shift can be detected and/or measured onany component of the substrate processing chamber. At operation, 209 arefined chucking voltage is determined using the impedance shift. In oneembodiment, which can be combined with other embodiments, the refinedchucking voltage is a minimum voltage value that will chuck thesubstrate to the support surface of the pedestal, for example, withoutany bow. In one example, the refined chucking voltage is the chuckingvoltage applied at the instant the impedance shift occurs. Determiningand using a refined chucking voltage facilitates increasing theprobability that a substrate will chuck to a support surface of apedestal in operations involving substrates, chambers, or pedestals thathave varying characteristics. Chucking a substrate facilitates reducingor eliminating a bow of the substrate and facilitates reducing theprobability of arcing occurring by removing or mitigating gaps betweenthe substrate support surface and a backside of the substrate. Areduction in the probability of arcing facilitates a reduction ofsubstrate defects and improved yield of substrate processing operations.Using a refined chucking voltage also allows operators the option of notusing high chucking voltages during substrate processing that wouldcause backside damage on the substrates. Reducing the probability ofbackside damage reduces the probability of substrate defects andimproves the yield of substrate processing operations.

In one example, the refined chucking voltage may be based on thechucking voltage at the instant of the impedance shift, plus anadditional amount of voltage to ensure chucking. For example, therefined chucking voltage may be equal to the chucking voltage at theinstant of the impedance shift, plus 5 percent, 10 percent, 15 percent,20 percent, 25 percent, or the like. In such an example, the refinedchucking voltage may be determined on a first substrate or batch ofsubstrates, and subsequently applied for multiple processing runs. Theinclusion of the additional amount of voltage increases the likelihoodthat the refined chucking voltage will facilitate chucking and thebenefits described herein for many process substrates, without the needfor performing method 200 on each individual substrate duringprocessing. It is also contemplated that method 200 may be performed oneach substrate during processing such that the refined chucking voltageis the optimal chucking voltage for each individual substrate.

In one optional embodiment, which can be combined with otherembodiments, the refined chucking voltage is determined by generating afirst image of a first impedance trace (e.g., a graph of impedance valuevs time, for one or more applied voltages) that is measured while theapplied chucking voltage and/or the ramped chucking voltage is appliedto the substrate for a predetermined time period, such as 5 or moreseconds. The first image of the first impedance trace is compared to asecond image of a second impedance trace measured for the same voltageapplied to a different substrate for the same time period. In oneexample, the different substrate is a flat silicon substrate that doesnot include a bow. If the first impedance trace matches the secondimpedance trace, then the applied voltage for the first impedance traceis determined to be the refined chucking voltage. If the first impedancetrace does not match the second impedance trace, then the appliedvoltage is ramped until the first impedance trace matches the secondimpedance trace. In one example, the first impedance trace matching thesecond impedance trace is used to confirm a proper voltage value for therefined chucking voltage when the refined chucking voltage is determinedusing the predetermined amount, as discussed above.

By using an impedance shift to determine the refined chucking voltage,the refined chucking voltage can be determined in real time duringsubstrate processing operations. Substrate processing operations neednot wait until a deposition process on a substrate has ended such thatthe substrate is inspected to determine if the applied chucking voltagewas sufficient. This facilitates savings for time and cost for thesubstrate processing operations, and facilitates improved yield.

At optional operation 211, the applied chucking voltage is adjusted tothe refined chucking voltage. Adjusting the applied chucking voltage tothe refined chucking voltage for subsequent processing can achieve thebenefits described herein with respect to the refined chucking voltagein a timely and cost-effective manner. The refined chucking voltage alsoallows substrate processing operations to efficiently account for andadapt to varying characteristics between different substrates. Forexample, if a new pedestal is used in substrate processing operations,that pedestal can have a differing thermal conductivity as compared tothe pedestal that was previously used. Adjusting the applied chuckingvoltage using the refined chucking voltage allows substrate processingoperations to efficiently adapt to the different properties of the newpedestal, as compared to the prior pedestal. This can be done each timea new pedestal is used. As another example, the refined chucking voltagemay be used to adjust a preselected value that was obtained fromspecifications for the new pedestal. In one aspect, one or moreoperations of the method 200 are performed each time a new pedestal isused in substrate processing operations.

As another example, if new substrates are used in a substrate processingchamber, the new substrates can have different bow characteristics thanpreviously processed substrates. Different bow characteristics caninvolve different chucking voltages that would eliminate bow in thesubstrates. Utilizing aspects discussed herein, a chucking voltage canbe applied to substrates which eliminates or mitigates bow without beingexcessive such that the likelihood of backside damage is reduced.

At optional operation 213, the refined chucking voltage is stored. Inone embodiment, which can be combined with other embodiments, therefined chucking voltage is stored in a memory for use in subsequentsubstrate processing operations. At optional operation 215, the refinedchucking voltage is applied. At optional operation 217, in response toapplication of the refined chucking voltage, one or more substrates arechucked to a support surface of a pedestal. The one or more substratesof optional operation 217 may include the substrate used in operation201. The one or more substrates of optional operation 217 may bedifferent than the substrate used in operation 201. The one or moresubstrates of optional operation 217 may include a second substrateand/or a third substrate that are different than the substrate used inoperation 201.

At optional operation 219, in response to application of the refinedchucking voltage, a bow of one or more substrates is reduced oreliminated. The one or more substrates of optional operation 219 mayinclude the substrate used in operation 201. The one or more substratesof optional operation 219 may be different than the substrate used inoperation 201. The one or more substrates of optional operation 219 mayinclude a second substrate and/or a third substrate that are differentthan the substrate used in operation 201.

At optional operation 221, a deposition process is conducted whileapplying the refined chucking voltage. For example, a film may bedeposited onto one or more substrates using one or more process gasesand generated processing plasma that cause a film to deposit onto one ormore substrates.

At optional operation 223, one or more of operations 201, 203, 205, 207,209, 211, 213, 215, 217, 219, and/or 221 are repeated on one or moreadditional substrates. The one or more additional substrates of optionaloperation 223 may include a second substrate and/or a third substratethat are different than the substrate used in operation 201.

The method 200 is not limited to the sequence or number of operationsillustrated in FIG. 2, but may include other implementations thatinclude re-ordering, repeating, adding, and/or removing one or more ofthe operations 201, 203, 205, 207, 209, 211, 213, 215, 217, 219, 221,and/or 223.

FIG. 3 is an illustration of an image 300 showing an impedance shift,according to one implementation. The image 300 illustrates an impedanceshift that occurs after a chucking voltage is ramped up. In theimplementation shown, a first chucking voltage, for example 550 Volts,is applied to a substrate for a predetermined time period, such as 20seconds. While the first chucking voltage is applied, a first impedancetrace 301 is generated by measuring impedance throughout the 20 seconds.A first impedance value 302 is measured after the predetermined timeperiod elapses. The chucking voltage is ramped up by a predeterminedvoltage increment, for example, of 50 Volts or for about 10 perdent, toapply a second chucking voltage (such as 600 Volts) to the samesubstrate for an additional period of time. In one one example, theadditional period of time is the same as first period of time, such as20 seconds. While the second chucking voltage is applied, a secondimpedance trace 303 is generated by measuring impedance throughout theadditional 20 seconds. A second impedance value 304 is measured afterthe second time period (e.g., 20 seconds) elapses. As illustrated in theimpedance of the second impedance trace 303 is substantially settledafter the additional 20 seconds has elapsed. This process is repeated,comparing the settled impedance to the previously-settled impedance,until a shift in impedance of at least a threshold value is determined.

A difference 305 between the second impedance value 304 and the firstimpedance value 302 of at least the threshold value (e.g., 0.5 Ohms)indicates a bow of the substrate is reduced or eliminated. The impedanceshift indicates that the second chucking voltage corresponds to achucking voltage at which chucking of a substrate to a support surfaceoccurs. Thus, excess application of power for chucking is unnecessary.

It is to be noted that the image 300 is only an example, and that otherimages may be generated or detected. Benefits of the present disclosureinclude reduced arcing, improved chucking of substrates to pedestalsupport surfaces, reduced backside damage, timely and efficientadaptation to changing equipment properties, enhanced yield, and loweroperational costs. Aspects of the present disclosure include applying achucking voltage to a pedestal; applying a chucking voltage to apedestal using a preselected value; ramping up the chucking voltageuntil an impedance shift occurs; detecting an impedance shift;determining a refined chucking voltage based on the impedance shift; andadjusting the applied chucking voltage to the refined chucking voltage.

It is contemplated that one or more of these aspects disclosed hereinmay be combined. Moreover, it is contemplated that one or more of theseaspects may include some or all of the aforementioned benefits.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof. The presentdisclosure also contemplates that one or more aspects of the embodimentsdescribed herein may be substituted in for one or more of the otheraspects described. The scope of the disclosure is determined by theclaims that follow.

What is claimed is:
 1. A method of chucking one or more substrates in asubstrate processing chamber, comprising: applying a chucking voltage toa pedestal, with a substrate disposed on a support surface of thepedestal; ramping the chucking voltage from the applied voltage;detecting an impedance shift while ramping the chucking voltage;determining a corresponding chucking voltage at which the impedanceshift occurs; and determining a refined chucking voltage based on theimpedance shift and the corresponding chucking voltage.
 2. The method ofclaim 1, wherein the impedance shift is an impedance shift of a radiofrequency energy generator that supplies radio frequency energy to thesubstrate processing chamber.
 3. The method of claim 1, wherein thedetecting the impedance shift comprises measuring the impedance shift.4. The method of claim 1, further comprising applying the refinedchucking voltage during a deposition process.
 5. The method of claim 1,wherein the applying the chucking voltage to the pedestal comprisesramping up the chucking voltage until the impedance shift occurs.
 6. Themethod of claim 1, wherein the refined chucking voltage is a minimumvoltage value that chucks the substrate to the support surface of thepedestal.
 7. The method of claim 1, wherein the refined chucking voltagereduces a bow of the substrate.
 8. The method of claim 1, furthercomprising generating a plasma.
 9. The method of claim 1, wherein theapplying the chucking voltage to the pedestal, the detecting theimpedance shift, and the determining the refined chucking voltage arerepeated on one or more additional substrates.
 10. A method of chuckingone or more substrates in a substrate processing chamber, comprising:applying a chucking voltage to a pedestal using a preselected value,with a substrate disposed on a support surface of the pedestal;detecting an impedance shift; determining a refined chucking voltagebased on the impedance shift; and adjusting the applied chucking voltageusing the refined chucking voltage.
 11. The method of claim 10, whereinthe impedance shift is an impedance shift of a radio frequency energygenerator that supplies radio frequency energy to the substrateprocessing chamber.
 12. The method of claim 10, wherein the detectingthe impedance shift comprises measuring the impedance shift.
 13. Themethod of claim 10, further comprising conducting a deposition process.14. The method of claim 10, wherein the applying the chucking voltage tothe pedestal using the preselected value comprises ramping up thechucking voltage towards the preselected value until the impedance shiftoccurs.
 15. The method of claim 10, wherein the refined chucking voltageis a minimum voltage value that chucks the substrate to the supportsurface of the pedestal.
 16. The method of claim 10, wherein the refinedchucking voltage reduces a bow of the substrate.
 17. The method of claim10, further comprising generating a plasma.
 18. The method of claim 10,wherein the applying the chucking voltage to the pedestal, the detectingthe impedance shift, and the determining the refined chucking voltageare repeated on one or more additional substrates.
 19. A controller forsubstrate processing chamber systems, comprising: a processor; and a setof computer instructions that, when executed, instruct the processor to:cause a direct current voltage generator to apply a chucking voltage toa pedestal, cause an impedance detector to detect an impedance shift ofa radio frequency energy generator, and determine a refined chuckingvoltage based on the impedance shift.
 20. The controller of claim 19,wherein the set of computer instructions, when executed, instruct theprocessor to store the refined chucking voltage in a memory.